Try to determine the characteristics of patients with different types of noninvasive breast lesions, with particular reference to those factors reputed to be preferentially associated with breast cancer, and to compare the findings with our similarly conducted breast cancer study. The proposal consists of two phases: case control interview study of 600 cases of noninvasive breast disease, and an incidence study of noninvasive breast lesions in a total community. In both phases, particular attention will be paid to the relative frequency of distinct histo-pathological forms in high and low risk sub-populations for breast cancer, i.e., European vs. Asian and African born. The characterization of the breast lesions will take account for the histological pattern, degree of atypia, and lymphoreticulo-endothelial response (LRE).